Re: [PATCH 2/4] libstdc++: Add a test for <version> FTM redefinitions

["Arsen Arsenović" <arsen@aarsen.me>]

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Jonathan Wakely <jwakely@redhat.com> writes:

> On 05/04/23 01:09 +0200, Arsen Arsenović wrote:
>>This test detects redefinitions by compiling stdc++.h with
>>-Wsystem-headers.  Thanks Patrick Palka for the suggestion.
>>
>>libstdc++-v3/ChangeLog:
>>
>>	* testsuite/17_intro/versionconflict.cc: New test.
>>---
>> libstdc++-v3/testsuite/17_intro/versionconflict.cc | 6 ++++++
>> 1 file changed, 6 insertions(+)
>> create mode 100644 libstdc++-v3/testsuite/17_intro/versionconflict.cc
>>
>>diff --git a/libstdc++-v3/testsuite/17_intro/versionconflict.cc b/libstdc++-v3/testsuite/17_intro/versionconflict.cc
>>new file mode 100644
>>index 00000000000..4191c7a2b08
>>--- /dev/null
>>+++ b/libstdc++-v3/testsuite/17_intro/versionconflict.cc
>>@@ -0,0 +1,6 @@
>>+// { dg-do preprocess }
>>+// { dg-additional-options "-Wsystem-headers -Werror" }
>>+
>>+// Test for redefinitions of FTMs using bits/stdc++.h.
>>+#include <bits/stdc++.h>
>>+#include <version>
>
> I'm concerned that this will fail if libc headers have macro
> redefinition errors, or anything else that would usually be ignored.
>
> We could make it more robust by changing <version> like so:
>
> --- a/libstdc++-v3/include/std/version
> +++ b/libstdc++-v3/include/std/version
> @@ -30,7 +30,9 @@
>  #ifndef _GLIBCXX_VERSION_INCLUDED
>  #define _GLIBCXX_VERSION_INCLUDED
>  +#ifndef _GLIBCXX_TESTING_SYSHDR
>  #pragma GCC system_header
> +#endif
>    #include <bits/c++config.h>
>  Then the test could define that macro instead of using -Wsystem-headers.
>
> Could you see if that works?

Good idea.  Both the positive and negative cases work when implemented
like this:


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From 98d302bab9a87d3f2daecf9d54d62f33ba216673 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Arsen=20Arsenovi=C4=87?= <arsen@aarsen.me>
Date: Wed, 8 Mar 2023 17:01:24 +0100
Subject: [PATCH 2/4] libstdc++: Add a test for <version> FTM redefinitions

This test detects redefinitions by compiling stdc++.h with
-Wsystem-headers.  Thanks Patrick Palka for the suggestion.

libstdc++-v3/ChangeLog:

	* testsuite/17_intro/versionconflict.cc: New test.
---
 libstdc++-v3/include/std/version                   | 5 ++++-
 libstdc++-v3/testsuite/17_intro/versionconflict.cc | 7 +++++++
 2 files changed, 11 insertions(+), 1 deletion(-)
 create mode 100644 libstdc++-v3/testsuite/17_intro/versionconflict.cc

diff --git a/libstdc++-v3/include/std/version b/libstdc++-v3/include/std/version
index cdd24248c57..1069bc6c9f6 100644
--- a/libstdc++-v3/include/std/version
+++ b/libstdc++-v3/include/std/version
@@ -30,7 +30,10 @@
 #ifndef _GLIBCXX_VERSION_INCLUDED
 #define _GLIBCXX_VERSION_INCLUDED
 
-#pragma GCC system_header
+// To facilitate testsuite/17_intro/versionconflict.cc
+#ifndef _GLIBCXX_TESTING_SYSHDR
+# pragma GCC system_header
+#endif
 
 #include <bits/c++config.h>
 
diff --git a/libstdc++-v3/testsuite/17_intro/versionconflict.cc b/libstdc++-v3/testsuite/17_intro/versionconflict.cc
new file mode 100644
index 00000000000..6c212980ab0
--- /dev/null
+++ b/libstdc++-v3/testsuite/17_intro/versionconflict.cc
@@ -0,0 +1,7 @@
+// { dg-do preprocess }
+// { dg-additional-options "-Werror" }
+
+// Test for redefinitions of FTMs using bits/stdc++.h.
+#define _GLIBCXX_TESTING_SYSHDR
+#include <bits/stdc++.h>
+#include <version>
-- 
2.40.0


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-- 
Arsen Arsenović

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